So, my english is not that good for a tut, but i'll try.
First create a new image like this:


3x3 pixels
Rember to select transparent background.

Draw a line using the Pencil Tool



Then, go to Edit, Define Pattern


Do this for eatch new pattern you draw, so you will have different options in the end.

Now lets do a 6x6 image:


Same thing, get the pencil, and will look something like this



Rember, do the Define Pattern after you draw, or it will be just waste of time.

a 10x10 pixels



Right, now just create a new layer in your userbar, and go Edit Fill (or just Shift F5) and select the pattern from the ones you made.

Here are my exemples


Well, standarts says about stripes, but this tut give you the idea that you can create block patterns, wave, dots... use your brain.
Just another hind for beginners, after you fill, try free transform, and flip horizontal, to change the scanline angle

Please vote on the poll if you dont want to replay. Thnks for the 3 of 160 viewers who voted...

Try putting step 1, step 2 in front of each step, makes the tuturial a lot better.